Beach Surveys and Biodiversity Study
In order to identify the location and abundance of oysters along the rocky and sandy shoreline of City Island, the first step was to document existing oyster populations. CIOR volunteers conducted beach surveys at low tide on a monthly basis to identify living oysters attached or not attached to substrate, as well as dead oyster shells, and all were counted and measured.
Volunteers monitor the range of biodiversity in the waters around City Island on an ongoing basis. This practice began in the summer of 2019, when mesh plastic bags filled with cured oyster shells were hung at five different locations, each bag exposed to different water conditions and flow. The cages were suspended from the bottom but fully submerged at low tide. Now CIOR uses Oyster Research Stations (ORS), provided by the Billion Oyster Project, which contain live oysters. These cages are monitored regularly, and the different species they attract, including oyster juveniles, are collected and analyzed. A wide range of species has been counted, measured, and photographed—from invertebrates such as tunicates and bryozoans to larger vertebrates, including eels and blackfish, as well as oyster predators (mud crabs and oyster drills) and oyster toadfish, which feed on crabs and snails. More than 900 animals comprising 33 different species were counted and measured during our initial research phase, enabling the establishment of a baseline for responses to restoration efforts at each location.
In order to identify suitable sites for eventual reef restoration, divers explore the shoreline of City Island and nearby locations to evaluate bottom substrate conditions. Naturally existing hard-bottom surface structure represents an ideal settlement surface for oyster larvae dispersed in the water during the spawning season and should be protected by our restoration efforts in order to promote reef enhancement.
Water quality fluctuates throughout the season and depends on location. Using water-quality measurement instruments, CIOR measures basic water-quality parameters around City Island at regular intervals. Parameters being measured by CIOR include water temperature, acidity or alkalinity of the water (pH), salinity, dissolved oxygen, turbidity, and water current velocity and tidal flow. This data is being explored and will be added to information available from other measurement stations near City Island, such as the EPA-approved Harbor Water Quality stations, and the monitoring in Eastchester Bay by Save the Sound and the Maritime College of SUNY. In collaboration with Save the Sound, CIOR will continuously monitor basic water-quality parameters using YSI EXO2 data loggers at two deployment sites.
Oyster Research Stations
Oyster Research Stations (ORS): The first steps in CIOR’s restoration efforts began in our partnership with the Billion Oyster Project to deploy these stations at four strategically placed locations around City Island. The ORS cages are filled with cured shell material that has been seeded with oyster spat and are then attached and hung off two docks and two moorings. CIOR members and eco-volunteers monitor the growth and mortality of the oysters in the cages on a regular basis between April and October.